Flow Structure and River Evolution at the Confluence Between Yellow River and Weihe River
The confluence of the Yellow River and the Weihe River is one of the typical large-scale river confluences in the Yellow River Basin,and is an important node for hydrodynamics and sediment transport in the middle and lower rea-ches of the Yellow River Basin.In order to further understand the three-dimensional flow structures and river evolution under the large width-to-depth ratio,large sediment load and complex topography,the flow fields of 15 cross-sections at the confluence were measured in site by acoustic Doppler velocity profiler(ADCP),and the hydrodynamic adjustment process was analyzed by kinetic energy correction coefficient(α)and momentum correction factor(β).The plan form of the river channel was derived from the remote sensing image data,and the evolution of the river channel at the confluence and upstream and downstream was analyzed.The results show that the hydrodynamic characteristics,such as the stagna-tion area,the maximum flow velocity area and the flow velocity recovery area were observed at the confluence of the Yellow River and the Weihe River,while obvious separation area was not found at the corner possibly due to the smooth transition of the confluence channel.At the beginning of the confluence,the inhomogeneity of flow velocity was strong(about 1.5 and 1.2 for the α and β,respectively)due to the large difference in velocity between the two flows and the narrowing of the channel.The values decreased rapidly with the widening of the river channel along the downstream.A strong secondary flow occurred in the cross-section at the beginning of the confluence,and its flow velocity can reach 1/8 of the main flow velocity.The secondary flow velocity decreased to the downstream.The remote sensing results demon-strate that the reach of the Yellow River which the confluence belongs to was unstable,and the confluence itself suffered from the deposition near the apex and the erosion near the opposite bank.
万方数据
维普
